Extreme Heat and Societal Vulnerability in a Changing Climate

Olga WilhelmiNCAR / Research Applications Programolgaw@ucar.edu

NCAR Colloquium on Statistical Assessment of Extreme Weather Phenomena under Climate Change, Boulder, CO June 9 2011

Defining “extreme” heat

Weather that has significant impacts is usually climatologically rare

Climatological perspective Absolute threshold (e.g., daily minimum temperature exceeds 25 °C) Tails of the climatological distribution for a location (e.g., temperature

above the 97th percentile).

Societal perspective High impact events that produce significant losses

Integrated perspective Societal impacts of extreme weather help determine climatological

measures of extremes (empirical models or time series)

Extreme heat and climate change are public health concerns Health impacts of extreme temperatures

Heat waves can be deadly, especially in cities Urban heat island

Impacts (health outcomes) are distributed unevenly Societal vulnerability (including adaptive capacity)

Heat-related deaths are preventable Ability to prepare, cope and adapt

Relationship between human health and extreme heat is a complex medical, social and environmental issue

Outline

Climate change, heat and health

Health outcomes from heat

Due to effort but inability of the human body to regulate its normal internal temperature over a period of time.

Direct outcomes: heat-related edema, rash, cramps, exhaustion, and stroke. Stroke (core body temperature above 41oC) is medical emergency. “classic” and “exertional” or “exercise-induced”

Indirect outcomes: respiratory, cardiovascular and diabetes-related conditions may be exacerbated by heat stress.

Patients being treated during the French heat wave of 2003. Photo: Martin Bureau/AFP

From U. Bickis, Health Canada

Russian heat wave” of 2010 (photo: Moscow Times) - “black swan” event

Extreme heat events

Extreme heat in hot climates

People are waiting for the bus in Phoenix, AZ. Photo: O. Wilhelmi

Thresholds

“The challenge lies in determining at which point the weather conditions become sufficiently hazardous to human health in a given population to warrant intervention.” (Kovats & Hajat, 2008)

Physical thresholds Epidemiological studies help identify “minimum mortality

temperature” T min, T man, T mean, Heat Indices, Air masses Population: all ages, over 55, 64-75, etc.

Physical thresholds vary among geographic locations and population groups Heat health outcomes depend on societal vulnerability and

adaptation to heat

Societal vulnerability

Vulnerability is the susceptibility of people or systems to damage or harm

Health outcomes are a product of extreme weather conditions and vulnerability.

Function of exposure - conditions of the natural and built environment that

position a system to be affected by extreme heat sensitivity - the degree to which a system is affected by extreme

heat adaptive capacity - the ability or potential of a system to modify its

features and behaviors to better cope with or adapt to extreme heat

Vulnerability is complex, dynamic, and spatially and temporally variable.

Scale of assessments Assessments help identify regions and

populations at risk and develop targeted interventions

National and regional assessments can mask communities living in marginal conditions

Hazard mitigation and climate change adaptation measures have to be adjusted for local ecology and appropriate level of decision making

Local-level assessment ensures more targeted intervention, response, adaptation. Community participation and buy in is critical.

Top down/bottom up approach is essential

Borden et al. 2007

O’Brien et al. 2004

Extreme heat vulnerability

Wilhelmi and Hayden (ERL, 2010)

Drivers

Climate change: Changes in extremes Uncertainty

Urbanization UHI, population density

Demographic changes Ageing Changing family structure

Ganguly et al. 2010

Ageing

Region Percent Population

Europe 27.4 189,118

Northern America 22.0 98,493

Latin America and the Caribbean 19.5 142,078

Oceania 18.7 9,581

Asia 17.3 906,053

Africa 7.1 141,538

Percent and Total Population Over Age 65, 2050

Source: Population Division of the UN Department of Economic and Social Affairs 2008

Urban heat island Urban heat island

“Urban” climate Paved surfaces and built

structures absorb shortwave radiation during the day and release long-wave radiation with increasing intensity in the afternoon and evening

Heat exposure The urban canyons reduce air

flow and trap heat near the surface

Land surface characteristics affect heat distribution within cities (e.g., parks vs parking lots)

Sensitivity

Demographic and socioeconomic characteristics Elderly Very young Obese Poor Mentally ill Socially isolated Pre-existing health conditions Lack air conditioning Work outdoors

Adaptive capacity

Adaptive capacity reflects a population’s potential to reduce harm in a changing environment, from current and future extreme weather.

Adaptive capacity is context-specific and dynamic

Influenced by availability of information and technology access to material, economic, and human resources institutional capabilities and knowledge, attitudes, practices, and beliefs. social capital, including social networks that connect individuals to

community resources

Measuring adaptive capacity is challenging adaptive capacity is often nuanced and best examined qualitatively or at the

household level

Adaptation and response Extreme heat preparedness and climate

adaptation plans

Coordinated Heat Watch/Warning systems

Programs that improve access to services/resources

Social and behavioral changes

Changes to physical environment

The Phoenix case study

Study objective: Understand adaptive capacity of the

vulnerable population Examine heat risk awareness and

responses in neighborhoods with variable degrees of vulnerability

The greater Phoenix, AZ area has an average of 26 deaths (1992-2009) every summer season from exposure to excessive heat (AZ Dept. of Health Services 2009).

In 2009, Maricopa County reported 71 heat-related deaths (V. Berisha, pers. communication, 2010).

Demographics of Heat Mortality in Phoenix/Maricopa County

Younger population at risk

Indoors / Outdoors mortality cases correlate with Older/ Younger population groups respectively

Combination of socio-economic and behavioral risk factors

Homeless population

Year 2005 n (%) 2000-2005 n (%)

N 49 146

Sex

Male 40 (82) 103 (76)

Female 9 (18) 33 (24)

Race

White 35 (71) 115 (85)

Black 7 (14) 10 (7)

Other 7 (14) 11 (8)

Ethnicity

Non-Hispanic 37 (76) 58 (62)

Hispanic 11 (22) 32 (34)

Other 1 (2) 3 (3)

Homeless 16 (33) 34 (25)

Place of death

Indoors 14 (38) 32 (34)

Outdoors 23 (62) 62 (66)

Age (years)

Mean (range) 59.8 (25-92) 56.4 (7-92)

Median 54 55

Source: Yip et al. 2008 Int J Biometeorolology

Exposure and sensitivity

Identifying relative importance of heat / health risk factors by exploring exposure/sensitivity and health outcomes on a neighborhood scale (Uejio et al. 2011) Urban ecology, characteristics of

the built environment, neighborhood stability

Aggregate demographic data cannot capture individual behaviors and responses Needs to be contextualized by

household-level data on adaptive capacity

Adaptive capacity: 2009 survey Questionnaire focused on indicators of adaptive capacity (e.g.,

KAP; social capital, household and community resources)

Three vulnerable neighborhoods• Diverse poverty levels (11%, 22%, 44%)• Ethnic and racial diversity• Previous cases of mortality and heat distress calls

359 semi-structured surveys at the randomly selected households

Neighborhoods demographics: Mean age: 40.9 Education: 32.8%- less than high school; 3.9 % - college graduate Race / Ethnicity: 67.7% Hispanic /Latino; 17.1% African American / Black;

11.6% Caucasian ; 3.9 % American Indian

Awareness of heat illness

%

Sym

pto

ms

iden

tifi

ed Dehydration/Intense thirst

Dizziness

Headaches

Nausea

Fatigue

Personal experience

Use of sunscreen

0 5 10 15 20 25 30 35 40 45 50

Awareness about extreme heat

Heard heat warnings

Local TV

Cable TV

Radio

0 10 20 30 40 50 60 70 80 90S

ou

rce

of

hea

t w

arn

ing

s

Sheridan (2007): Phoenix survey of elderly showed 90% were aware of heat warningsPhillips and Morrow (2007); Morss and Hayden (2010): television a trustworthy and expert source of hazard information and recommendations

%

Awareness of available resources for coping with heat

Respondents were unaware of the resources available to them through city programs to repair air conditioners and assist with payment of electric bills.

In 2009 Phoenix had 51 hydration stations and 42 heat refuge stations (cooling shelters).

Know about heat refuge station

Know where heat refuge stations are

Used heat refuge stations

0 5 101520253035%

Coping with extreme heat

%

Altering daily outdoor activi-ties

Staying indoors

Drinking water

0 10 20 30 40 50 60 70 80 90

Indoor and outdoor heat risk

Feel most at risk outdoors

Use bus daily

Cars without A/C

Feel too hot at home

Have A/C at home

Cost of electricity prevents from using A/C at home

Broken or non-functional A/C

0 10 20 30 40 50 60 70 80 90 100%

0

10

20

30

40

50

60

70

80

90

100

Too hot inside home

A Neighborhood

B Neighborhood

C Neighborhood

Chi-square = 29.87P = .000

Differential coping capacity

Chi-square = 19.85P = .000

Social capital and community networks

0

10

20

30

40

50

60

70

80

90

100

Safe in Neighborhood

A Neighborhood

B Neighborhood

C Neighborhood

Improving outcomes Access to information

All of the neighborhoods could benefit from improved access to information about available city-wide resources to reduce risk from extreme heat.

Weather – Public Health partnerships Dissemination of critical information about resources for coping along with heat

warnings. Potential role for local TV broadcast meteorologist.

Social capital Multi-service centers could provide a cooling shelter coupled with community

outreach programs. Community-wide efforts to ensure that neighbors, social workers and home

health care providers check on socially isolated residents.

Surveys can provide more up-to-date information on vulnerability Impact of unemployment (38%) and limited household resources contributed to

higher vulnerability in neighborhoods with higher SES

Need better understanding of social and behavioral aspects of vulnerability to ensure more targeted interventions and adaptation strategies.

Current and future impacts of extreme heat

How does extreme heat in present and future climate affect human health in environmentally, socially and economically diverse urban settings?

Need to understand the relationships among global climate change local meteorology and extreme events urban land use local environmental characteristics previous health outcomes social vulnerability heat mitigation responses and climate adaptation strategies

System for Integrated Modeling of Metropolitan Extreme heat Risk (SIMMER)

NASA ROSES (09-IDS09-34)2010-2013

RAL

CGD

IMAGe

SIMMER project goals

Inform climate change adaptation and public health interventions in order to reduce current and future vulnerability to extreme urban heat

Advance methodology for assessing current and future urban vulnerability from heat waves through integration of physical and social science models, research results, and remote sensing data;

Develop a system (SIMMER) for building local capacity for heat hazard mitigation and climate change adaptation in the public health sector.

Filling the gaps

Determining the combined impact of extreme heat and the characteristics of urban environmental and social systems on human health

Characterizing societal vulnerability and the responses (i.e., mitigation and adaptation strategies)

Improving representation of urban land cover and its accompanying radiative and thermal characteristics at local and regional scales

Characterizing and modeling present and future extreme heat events at regional and local scales

Quantifying uncertainty

Summary Empirical studies and model simulations suggest increasing

health risks associated with climate change and extreme heat events

Relationship between human health and extreme heat is a complex medical, social and environmental issue

Research challenges: Thresholds for warnings and advisories Measuring adaptive capacity Changing patterns of extreme events Dynamic social vulnerability and adaptive capacity Predictive heat health models

Preparedness and adaptation: Reducing vulnerability Engagement of stakeholders from both the top-down and the

bottom-up allows the opportunity to better characterize health risks and develop policies for public health climate adaptation

Thank you!

For more information: Wilhelmi OV, Hayden MH. 2010. Connecting people and place: a new

framework for reducing urban vulnerability to extreme heat. Environmental Research Letters. 5:014021

Hayden MH, H Brenkert-Smith, OV Wilhelmi. Differential Adaptive Capacity to Extreme Heat: A Phoenix, AZ Case Study. Submitted to Weather, Climate and Society

Morss, RE, OV Wilhelmi, G. Meehl, L. Dilling. 2011. Improving Societal Outcomes of Extreme Weather in a Changing Climate: An Integrated Perspective. Annual Review of Environment and Resources